1691250985 has 4 divisors (see below), whose sum is σ = 2029501188. Its totient is φ = 1353000784.

The previous prime is 1691250929. The next prime is 1691250997. The reversal of 1691250985 is 5890521961.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5890521961 = 2143 ⋅2748727.

It can be written as a sum of positive squares in 2 ways, for example, as 1342196496 + 349054489 = 36636^2 + 18683^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1691250985 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 169125094 + ... + 169125103.

It is an arithmetic number, because the mean of its divisors is an integer number (507375297).

Almost surely, 2^1691250985 is an apocalyptic number.

It is an amenable number.

1691250985 is a deficient number, since it is larger than the sum of its proper divisors (338250203).

1691250985 is an equidigital number, since it uses as much as digits as its factorization.

1691250985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338250202.

The product of its (nonzero) digits is 194400, while the sum is 46.

The square root of 1691250985 is about 41124.8220056938. The cubic root of 1691250985 is about 1191.4322573037.

The spelling of 1691250985 in words is "one billion, six hundred ninety-one million, two hundred fifty thousand, nine hundred eighty-five".